Best Practices

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Laipuitlang, AizwalLaipuitlang is located amidst hilly terrain of Aizwal. The area receives very high rainfall both from the southwest and northeast rainfall. The average annual rainfall of the area is 2049.7 mm and the number of rainy days is 110. The area falls in the high rainfall region of the country. Considering the greater number of rainy days, storage is the best option. Overall there is scarcity of water supply in the region.

The pumping station for supplying water is Tlawng river downhill and as the Public Heath Department (PHED) has to depend on the pumping machineries and electric supply to supply water in the region, the Government of Mizoram opted to harvest rain from the surface and rooftops of two reservoirs in Laipuitlang. The rainwater collected passes through the slow sand filter and ultimately stored in the two reservoirs.

Residence of A R Shivakumar, BangaloreThe residence of A R Shivakumar is located on a ridge in the city of Bangalore and there is no municipality water connection in the site. The only source of water is rainwater supplemented by groundwater which is extracted through one borewell in the premises. About 70 % of the rainwater is diverted to the northern side of the house and gets stored in an overhead tank of 4,500 litres capacity placed on the ground floor roof.

Before passing to the tank, the rainwater passes through a stabilization tank, whereby the silt gets settled. This water is generally used for non potable purposes like cleaning, washing etc. The overflow of the tank flows to an underground sump of 25,000 litres capacity. This is a L shaped tank and is used for drinking and cooking only. About 30 % of the rainwater from the roof gets diverted to pop up filters placed on the ground level.

The filtered water free of suspended and floating particles gets stored in another sump of 10, 000 litres capacity. The underground sumps are interconnected. The water from the overhead tank is used during rainy season and that from the underground sumps are used during the non rainy seasons. The rainfall falling on the backside of the building percolates to the ground through four recycled plastic drums with their bottom cut and buried underground.

The interconnected drums recharge the groundwater. Care has been taken that not a single drop of water passes out of the premises. The groundwater recharge has improved the groundwater level. Before the implementation of the system, the groundwater level in the surrounding area was 61 m bgl but recently groundwater is available at the depth of 9 m bgl.

Cygnus Microsystems, HyderabadCygnus Microsystems is located in Cherapally. This is an industrial area that does not have municipal water supply and the only source of water is groundwater and is pumped through 107 m deep borewell. The organization was forced to invest Rs. 6000 per month on bottled water for drinking purpose. Apart from this the groundwater was declining at an alarming rate in the area. The management feared that they would have to outsource water from outside for cooking, toilets and gardening. They started harvesting rain from 2004. There are two tanks in the premises- Drinking Water Tank and Gardening Tank.

Two pits have been made to harvest the excess uncollected rainwater and any overflow from the rainwater collection tanks. Drains, running along the building, channel this excess water to the harvesting pits. One of the harvesting pits is inside the premises. The overflow from this is diverted to another recharge pit just outside the premises. A gate arrangement is made to hold the water for some time so that the first pit has chance to absorb the water. These rainwater harvesting pits are located at the lowest point of the plot. They contain layers of stone metal and brickbats to increase their absorption capacity.

The Drinking Water Tank is connected to the main building block. The area of the roof is 645 sq m but only one third of the rooftop is harvested. According to the Manager Ms. Babita, cleaning of a smaller catchment is easier for them. The management is not thinking of harvesting the entire rooftop area as they are satisfied with the volume of water that is presently collected. The water from the rooftop comes down the pipes through three outlets only on the backside of the building.

The rainwater first passes through a filtering tank, which has gravels of different sizes. The water passes from the filter to the sump of 65,000 litres capacity. The stored water is again passed through aqua guard for complete purification before drinking. Every day about 60litres of water is used for drinking and the water stored is sufficient to last for one full season. Pay back period is 3-4 years. Maintenance includes chlorination of water and cleaning of the catchment, sump and filter once a year.

The Gardening Tank is connected to the Parking Shed area. The area of the roof is 275 sq.m. The water from the shed of Galvanized Aluminium collects in the gutter of same material and passes down the pipe at only one point of the roof. The water is then passed to a filtering tank, which contains boulders of different sizes.

The water from this tank passes to a sump from where water is pumped for gardening purpose. The water supplements the bore water and is sufficient for one complete season to water the plants during the scarcity period. Maintenance includes only cleaning of the catchment, sump and filter once a year.

Chintamani Vidyapith, PuriThe school is located in 8 post Rench in Nimapara Block. The only source of water is groundwater. There are 700 pupils in the school and the rainwater caters mainly to students. The groundwater of Chintamani Vidyapith has salinity content above the permissible limit (according to BIS). The water is unfit for drinking or even washing hands or cleaning utensils.

The harvested rainwater is stored in underground sump and pumped through hand pump. A soak pit has also been made in the area to absorb extra rainwater falling in the area. The rainwater stored in tanks is used only for drinking, cleaning and flushing. The quality of groundwater has been improved due to recharging of rainwater through soak pit.

The area of the rooftop is 116 sq m and the water from the rooftop is directed towards the downtake pipe through one outlet. The water then flows to the first filtration tank, which has a bucket with coconut coir. The bottom of the bucket has got many holes through which the filtered water passes to the main tank. From here the water goes to the next filtration tank.

Here there are three layers of filtering material namely sand pebble and gravel kept one above another. These materials are kept in layers and the thickness of each layer is 1 ft. From here the rainwater passes to an underground sump. Hand pump is used to extract the stored water for different purposes like drinking, cleaning and washing.

There are two large ponds in the campus, which they locally call “pokhori” and the pond water not only recharges the groundwater but also used for washing and cleaning during peak summers. The harvested water lasts for eight months only.

The NGO claims that the system has zero maintenance as the rooftop is kept clean every day by the students. The staff and the students clean the sump and the filtering material themselves.

Naka Gate Slum, Bhubaneshwar
This slum is located in the Khandagiri area of Bhubaneshwar. This is a rocky area and exposure of lateritic rocks occurs all over the place. Although there are 5 open wells in the area, but getting a proper water supply to the school is very difficult. The school was constructed by RSSO in 2005 but the school remained non functional due to water scarcity.

The area of the rooftop is 22.3 sq m. The rainwater from the sloping roof of GI sheet is collected in gutter and transmitted to the first storage tank. Once this tank is full, the overflow passes to the next tank and so on. At the collection point there is an iron bucket to strain away large impurities as mentioned above. There are three storage tanks. From the storage tanks the water passes to the taps of the toilets through a filtration tank.

The NGO claims that the system has zero maintenance as the rooftop is kept clean every day by the teachers of the school. The iron bucket is also cleaned every month. The same group of people also cleans the filter material every year.

Sterling Green View Phase-II, Bhopal
The row houses in Sterling Green View Phase II suffered critical water problem before 2005. There are three tube wells in the area and ground water is the only source of water in the area. So the residents opted for Rainwater Harvesting for two rows of houses in two phases at a cost of Rs 6, 500 in the year 2005 and Rs 17,000 in the year 2007.

Rainwater Potential = 1146.7 x 1485 x 0.8 = 13,62,280 litres

There are two rows of houses. In one row there are ten houses and in the other row there are five houses. The water from the rooftop comes down the pipes at the backside of both the rows. A main pipe on each row, which is connected to the Amber Filter, joins these pipes. First flushing system is seen there. This filter contains charcoal, lime and sand. The filtered water then recharges two service tube wells in the area. The row that contains ten houses recharges the service tube well which is 51 m deep and the row, which contains five houses, recharges another service tube well which is 75 m deep.

Raheja Solitaire, Goregaon(W), MumbaiConsultation and implementation work of Rain Water Harvesting was successfully carried by M/s. N.S. & Associates in the fair season of March 2005 prior to 26.7.2005 heavy flooding in Mumbai. The plot is situated at the south west side of Goregaon rail over bridge, off. S.V. Road. The area of the plot is approx. 5093 sq. mt. having slight slope towards the road side. A building having stilt + 14 stories, club house etc. was proposed and constructed on site. There are 8 flats in each floor i.e. total 110 flats. Storm water drain was constructed having slope from west to east (road side).

The catchment of water harvesting system is the surface that directly receives the rainfall and provide water to the system. It is paved area of terrace (800 sq.mt.) podium (1100 sq.mt.) and rest of paved area of the plot. There are two bore wells having yield of 25000 ltrs/day and 45000 Ltrs/day. As per soil investigation report, a layer of weathered basalt is observed about 4.5 m below the ground above which lies the hard clayey soil.

Water required for flushing purpose is 27,500 ltrs/day. (110 flats x 5 person per flat x 50 ltrs. = 27,500 ltrs.) Considering the site condition and flushing requirement, consultant had proposed and implemented 2 units of Rain Water Harvesting system. Rainwater Harvesting System consists of recharging of groundwater through borewells:

Unit I of Rainwater Harvesting System is at backside of main building using terrace and podium water for recharge of the bore well. Recharging of borewell where all the terrace water is diverted. As per planning first the water is passed through filtration tank and then transferred to the borewell through gravitational force. The filter is the combination of graded sand and metal to allow rainwater to percolate and to trap suspended and floating material.

Unit II Rainwater Harvesting System is near main gate, using paved area water for recharging of bore well using settling tank and filteration tank and then transferred for recharging borewell.

Society saves annually Rs.45000/-

This design has given extraordinary results during monsoon of 2005 and 2006. During 26.7.2005 floods, entire rain water was recharged in the soil and there was absolutely no flooding in the plot. There was water logging outside building during 26.7.2005 floods but rainwater harvesting system has helped to avoid flooding in the building. Rainwater harvesting has helped in improving the yield of borewells and it has improved the quality of water. The water from rainwater harvesting system is utilized for only secondary purpose i.e flushing, gardening and car washing.

PRINCE OF WALES MUSEUM KALAGHODA-MUMBAI
The Museum has a yearly requirement of 36,50,000 Litres i.e. 10,000 Liters / Day
for gardening. To meet this requirement they designed a recharge pit of 5 m x 5 m x 4 m depth. “V” wire rainwater filter Screen (SS304) from Johnson’s is installed on the mouth of borewell casing pipe.

A valve chamber to divert first rainfall water into storm water drain is installed (Size: 0.9 m x 0.9 m x 1.5 m depth). All rainwater downtake pipes in the front side of Museum building are connected to the recharging pit. Phase II proposed to be implemented after monsoon season is over.

Ayurveda College Hospital, Thiruvananthapuram
On the roof, a 1000 litres tank is placed for each rainwater storage tank on the ground. The water is pumped into these tanks and used for gardening and other non potable purposes. The hospital has total number of 9 tanks with total capacity of 2,25,000 litres.
The project was completed in May 2006 with a total cost of 7 lacks.

SPECIFICATIONS
Total area of the plot = 6 acres
Area of rooftops / terrace = 3800 sqm.
Area of unpaved surfaces = 16476 sq m
Area of paved surfaces = 4000 sq m

Shivani Apartment, Chennai
Shivani Apartments in Chennai stressed for water, was dependent on the borewell for their water supply. This dependence led to depleting ground water levels. They decided to invest in rainwater harvesting recharge structures which has resulted in improvement in the existing bore wells.

Around 40 pits were dug around the premises of the apartment. Size of each pit is 4 feet dia and 1.5 feet depth 1’ dia and 10’ deep auger. 6 recharge wells were dug, each with a dimension of 10’ dia and 10’depth with 1’ dia and 10’ deep auger. The installation was complete by May, 2003. The project cost was 5 lakh.

Mysore
The Karnataka Bank branch in Kuvempu Nagar, Mysore, is a two-storied building with a basement for parking vehicles. In the rainy season, the basement would be completely flooded and several vehicles were severely damaged. To address this problem, the bank built an underground tank to collect the flood water and later this water would be pumped out onto the storm water drains.

Mr. B M Ramesh, the bank manager, decided that it would be a good idea to use the water to recharge the aquifer and prevent wastage of the collected rainwater. As a result, the water level in the borewell rose significantly and there was also a reduction of hardness. During the monsoon season at least 10,000 litres would percolate into the aquifer everyday. Seeing the results, the bank staff constructed a recharge borewell and today there is absolutely no flooding in the basement.